1. Field of Invention
The present invention relates to a sprayer, in particular, a dishwashing sprayer.
2. Description of Related Art
A sprayer of this type is known, for example, from EP-A-0 656 503. It has a tubular handle which bears, at its inlet end, a connection nipple for a supply hose and, at its outlet end, a spray head and a shut-off valve. The shut-off valve can be actuated by means of a hand lever counter to the force of a restoring spring which is intended for closing purposes. Within the handle, an inner tube extends from the connection nipple to the shut-off valve. This tube is enclosed by an elastomeric hose and has spaced-apart openings into the interior of the hose. Rapid closure of the shut-off valve produces a temporary positive pressure as a result of the water column of the water fed being slowed down too rapidly. In order to damp this pressure surge in the supply line with its adverse effects, use is made of the inner tube with the hose fitted over it, the latter temporarily expanding, as a compliant wall, into a cavity in the handle.
A further sprayer with a damping system for pressure surges which is based on the same principle is known from EP-A-0 704 252 and corresponding U.S. Pat. No. 5,732,884.
During closure of the shut-off valve, the resulting pressure surge moves from the shut-off valve, through the inner tube, in the direction of the connection nipple. During this movement, the pressure surge reaches the openings one after the other, which results in the pressure surge being damped in a step-like manner until it has reached the connection nipple.
In order to prevent or reduce pressure surges, it is also known, from CH-A-647 165, to allow the shut-off valve of a dishwashing sprayer to close in a delayed manner even when the hand lever is rapidly released. A valve piston which is spring-loaded in the closing direction of the shut-off valve, and is operatively connected to the latter, is guided in a cage and has a connecting channel, which acts as a restrictor, running through it. By means of the connecting channel, a cage chamber which is bounded by the cage and the valve piston is connected to the flow channel for the water, which is bounded by a cylinder tube arranged in the interior of the handle. As a result of the restricting action of the connecting channel, it is only possible for a limited quantity of water per unit of time to flow into the cage chamber and/or to be displaced out of the latter. This limits the speed at which the shut-off valve can be opened and closed.